Perfluorocarbon‐Loaded and Redox‐Activatable Photosensitizing Agent with Oxygen Supply for Enhancement of Fluorescence/Photoacoustic Imaging Guided Tumor Photodynamic Therapy

Abstract The wide clinical application of photodynamic therapy (PDT) is hampered by poor water solubility, low tumor selectivity, and nonspecific activation of photosensitizers, as well as tumor hypoxia which is common for most solid tumors. To overcome these limitations, tumor‐targeting, redox‐activatable, and oxygen self‐enriched theranostic nanoparticles are developed by synthesizing chlorin e6 (Ce6) conjugated hyaluronic acid (HA) with reducible disulfide bonds (HSC) and encapsulating perfluorohexane (PFH) within the nanoparticles (PFH@HSC). The fluorescence and phototoxicity of PFH@HSC nanoparticles are greatly inhibited by a self‐quenching effect in an aqueous environment. However, after accumulating in tumors through passive and active tumor‐targeting, PFH@HSC appear to be activated from “OFF” to “ON” in photoactivity by the redox‐responsive destruction of the vehicle's structure. In addition, PFH@HSC can load oxygen within lungs during blood circulation, and the oxygen dissolved in PFH is slowly released and diffuses over the entire tumor, finally resulting in remarkable tumor hypoxia relief and enhancement of PDT efficacy by generating more singlet oxygen. Taking advantage of the excellent imaging performance of Ce6, the tumor accumulation of PFH@HSC can be monitored by fluorescent and photoacoustic imaging after intravenous administration into tumor‐bearing mice. This PFH@HSC nanoparticle might have good potential for dual imaging‐guided PDT in hypoxic solid tumor treatment.